A process for the solventless polymerization of brominated styrenes includes blending monomers of brominated styrenes with a polymerization initiator, feeding the monomer/polymerization initiator mix into a prepolymerizer wherein the monomers begin to polymerize, and feeding the monomer/polymerization initiator mix and the partially polymerized bromostyrene into a screw-type extruder to drive the polymerization to a high degree of completion in a short period of time. Optionally, the monomers may be preheated before mixing with the initiator, or a heater may be included in the prepolymerizer.
